As I'm sure is true fore everyone, almost all my robo calls come from the same area code and often the same first 3 numbers as my number. I always mark them as spam. Google's spam detecting AI is so bad that it hasn't yet started blanket blocking all unknown callers that meet that criteria. If only you could set your own rule...
You can block these types of calls. In the app tap on the Block List (circle with the line through it along the bottom.) Then tap on the "+" and select "Numbers that begin with." You can then input any area code or prefix you want. You can also block by country code this way. https://www.hiya.com/ Google probably has more to lose by blocking calls from a neighboring doctor (or political candidate) than allowing a junk call to go through. Until the FCC acted carriers were prohibited from “censoring” sales calls.We call these calls the neighbor scam.